The goal of this research is to improve treatment outcome for marijuana-dependent individuals. In this competing renewal, we propose to build on the early findings of our current NIDA-funded (R01) marijuana treatment study in which improved client outcomes were associated with greater treatment attendance, greater client self-efficacy, and greater use of coping skills. We intend to use a contingency management paradigm to provide tangible reinforcement for completing homework assignments that are designed to enhance coping skills. It is anticipated that this will result in greater homework compliance, leading to greater self-efficacy regarding one's ability to cope with high-risk situations. Improved self-efficacy will enhance the likelihood of employing coping skills in high-risk situations, thereby increasing the probability of achieving and maintaining abstinence. Participants will receive an intervention combining one session of motivational enhancement therapy with eight sessions of cognitive-behavioral coping skills therapy (MET+CBT). A contingency management procedure will be added to this intervention, providing reinforcement for completion of homework, as verified by call-ins to an Interactive Voice Recording (IVR) system. Outcomes will be compared to an MET+CBT intervention in which reinforcement will be provided for marijuana-free urine specimens, and to a control group that receives case management. Recruitment of 234 marijuana-dependent participants will occur over a three-year period. They will be randomly assigned to one of the three 9-session interventions. Treatment will be individual, manualized, and provided on an outpatient basis. Pretreatment assessments will obtain baseline data;follow-up assessments at three-month intervals for one year will evaluate marijuana use outcomes, other drug or alcohol use, and psychosocial functioning. It is anticipated that the intervention in which completion of homework is reinforced will result in the best outcomes. The mechanisms by which the interventions result in behavior change will be the specific focus of attention in the proposed study. Public Health Relevance: Marijuana is the most widely used illicit drug, which 4% of the population become dependent on. To date, studies of treatment for marijuana dependence have shown reductions in use, but low rates of abstinence. The proposed research focuses on a treatment intended to increase the abstinence rate, and on identifying mechanisms of change. If successful, the proposed intervention would provide a powerful tool for ameliorating a major public health problem.